Like you, I listen to nature while riding outside.
On my trainer, I use Spinerval DVD's for my workout, and supplement that with talk radio and/or TV shows. I have remotes for all within easy reach.
On the stationary bicycle at the gym, I read a book - makes the time go real fast!
I might give music a try, however. I have really gotten into singing lately, doing several solos and joining a couple of singing groups. My wife and I are currently practicing for a duet we will be singing in church in March. Music is another GREAT release/activity, in addition to bicycling and weight lifting.
Hey, I hope to get some time to just "sit" someday. Not yet, though.
Good topic.